A printhead is the device in printers, copiers, and multi-function products which sprays droplets of ink onto a sheet of paper. A number of printers, copiers, and multi-function products utilize heater chips in their printheads for discharging ink drops from one or more ink vias. Inkjet heater chips typically contain one or more ink vias as well as arrays of heaters located next to an ink via. The heaters provide thermal energy that causes the discharge of a droplet of ink. Chip bondpads are used to power the heaters by providing electric current to the heaters. Each chip bondpad usually has a corresponding tab circuit connection, tab trace, and electrical connection to the printing device.
The minimum number of bondpads required to power the heater arrays is determined by the amount of current required to fire the number of heaters simultaneously to achieve the desired performance in discharging ink droplets. Typically, in inkjet heater chips with one ink via, heater chip bondpads supply power only to heaters located on the same side of the ink via as the chip bondpads. Similarly, in inkjet heater chips containing multiple ink vias, a given bondpad supplies power to heaters on one side of the ink via or the other, but not both. Bondpads consume chip area. The on-chip routing of heater power from the bondpad to the heater arrays is also a contributing factor to overall chip size. The higher number of chip bondpads and power routes also increase the cost of the heater chip. Therefore, what is needed is a way to minimize the number of chip bondpads necessary to power the heater arrays on the chip.